The present invention relates to energy or data transmission system with improved electromagnetic interference (EMI) immunity.
In a variety of environments, signals must be transmitted between diverse sources and circuitry that uses those signals while maintaining electrical (i.e., galvanic) isolation between the sources and the using circuitry. Electrical isolation can prevent extraneous transient signals, including common-mode transients, from inadvertently being processed as status or control information. Also, among other known objectives and uses, electrical isolation is used to protect the equipment from shock hazards, or to permit the equipment on each side of an isolation barrier to be operated at a different supply voltage. For example, isolation is typically needed between microcontrollers and devices or transducers that use microcontroller output signals.
Coil (or transformer) based isolators are widely used signal transformers in which a primary winding and a secondary winding are inductively coupled. Conventional transformers, however, transmit pulses by switching one terminal of the inductor on and off to a power supply voltage. Thus, in the conventional transformers, the signaling current is an integral part of the supply current and any electromagnetic interference on the power supply voltage severely affects the signal transmission. Therefore, the inventors perceive a need in the art for an isolated digital signal transmission mechanism with improved EMI immunity.